Proportionately we would not. Sure, we would each pay 20%, but not all 20%s are created equal.

The problem with Forbes’ flat tax rate is the proportion of income that goes to supporting oneself among the different tax brackets. As income increases, one can easily pay not only a greater net amount but also a higher percentage. One family might need 80% of income to pay the bills while a higher income family might only need 50% to cover expenses. Staggered tax brackets allow you to dip equally by proportion into each bracket’s “surplus” income (in theory; we have too many loop holes). A flat tax usually ends up taxing the poor too much and the rich too little; if we want to ease the burden on the poor, we lose significant tax income from the rich.